Publications by authors named "Pretesh R Patel"

Purpose: This study aims to develop a robust, large-scale deep learning model for medical image segmentation, leveraging self-supervised learning to overcome the limitations of supervised learning and data variability in clinical settings.

Methods And Materials: We curated a substantial multi-center CT dataset for self-supervised pre-training using masked image modeling with sparse submanifold convolution. We designed a series of Sparse Submanifold U-Nets (SS-UNets) of varying sizes and performed self-supervised pre-training.

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Purpose: While the benefit of short-term androgen deprivation therapy (ADT) has been established for patients with intermediate-risk (IR) prostate cancer (PCa) receiving dose-escalated external beam radiation therapy (EBRT), the role of ADT for patients treated with brachytherapy (BT) with or without supplemental EBRT (sEBRT) is less clear.

Material And Methods: We conducted a single-institution retrospective analysis of men with National Comprehensive Cancer Network (NCCN) unfavorable IR (UIR) PCa. All patients received BT with or without sEBRT, and were stratified by the receipt of 4-6 months of ADT.

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Background: Bi-parametric magnetic resonance imaging (bpMRI) has demonstrated promising results in prostate cancer (PCa) detection. Vision transformers have achieved competitive performance compared to convolutional neural network (CNN) in deep learning, but they need abundant annotated data for training. Self-supervised learning can effectively leverage unlabeled data to extract useful semantic representations without annotation and its associated costs.

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Purpose: To review our initial experience with proton-based SBRT to evaluate the planning outcomes and initial patient tolerance of treatment.

Patients And Methods: From Sep. 2019 to Dec.

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Purpose: Rectal toxicity after prostate cancer (PCa) radiation therapy (RT) may be greater with protons compared with photon intensity-modulated RT, perhaps due to lateral penumbra and end-of-range uncertainty. Rectal spacers (RSs) have been shown to mitigate RT-associated acute/late rectal toxicity in men treated with photons. The relative benefit of RS in men treated with protons versus photons is unknown.

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Purpose: Whole-pelvis (WP) radiation therapy (radiation) improved biochemical relapse-free survival (bRFS) compared with prostate bed (PB)-only radiation in the Radiation Therapy Oncology Group 0534, but was performed in an era prior to positron emission tomography (PET) staging. Separately, 18F-fluciclovine PET/CT-guided postprostatectomy radiation improved 3-year bRFS versus radiation guided by conventional imaging alone. We hypothesized that patients who were changed from WP to PB-only radiation after PET would have bRFS that was: (a) no higher than patients initially planned for PB-only radiation; and (b) lower than patients planned for WP radiation without PET guidance.

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Background: FLASH radiotherapy (FLASH-RT) with ultra-high dose rate has yielded promising results in reducing normal tissue toxicity while maintaining tumor control. Planning with single-energy proton beams modulated by ridge filters (RFs) has been demonstrated feasible for FLASH-RT.

Purpose: This study explored the feasibility of a streamlined pin-shaped RF (pin-RF) design, characterized by coarse resolution and sparsely distributed ridge pins, for single-energy proton FLASH planning.

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Background: Recipients of radiation therapy (RT) for head and neck cancer (HNC) are at significantly increased risk for carotid artery stenosis (CAS) and cerebrovascular disease (CVD). We sought to determine (1) cumulative incidences of CAS and CVD among HNC survivors after RT and (2) whether CAS is associated with a RT dose response effect.

Methods: This single-institution retrospective cohort study examined patients with nonmetastatic HNC who completed (chemo)RT from January 2000 through October 2020 and subsequently received carotid imaging surveillance ≤2 years following RT completion and, in the absence of CAS, every 3 years thereafter.

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Purpose: This study explored the feasibility of a streamlined pin-shaped ridge filter (pin-RF) design for single-energy proton FLASH planning.

Methods: An inverse planning framework integrated within a TPS was established for FLASH planning. The framework involves generating a IMPT plan based on downstream energy modulation strategy (IMPT-DS), followed by a nested spot reduction process to iteratively reduce the total number of pencil beam directions (PBDs) and energy layers along each PBD for the IMPT-DS plan.

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Purpose: Early exposure to oncology care during the preclinical years of medical school may translate to increased student interest in oncology-related fields and improved understanding of oncologic treatment modalities, including radiation oncology. Many schools incorporate problem-based learning (PBL) into the medical school curriculum; this is an opportunity to immerse students in oncologic case management. We describe the effective incorporation of one course into the medical school curriculum that may be replicated at other institutions.

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Article Synopsis
  • - The study addresses the limitations of cone-beam computed tomography (CBCT) scans in adaptive radiotherapy by developing a conditional diffusion model to enhance the quality of CBCT to match that of standard CT scans for better image-guided treatment.
  • - A conditional denoising diffusion probabilistic model (DDPM) using a U-net architecture was trained on images from deformed planning CT and CBCT pairs, demonstrating its effectiveness in two patient studies — one for brain and another for head-and-neck cases.
  • - The results indicated substantial improvements in the generated synthetic CT (sCT) quality over the original CBCT, as measured by metrics like mean absolute error (MAE) and peak signal-to-noise ratio (PSNR
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Importance: Very high-risk (VHR) prostate cancer is an aggressive substratum of high-risk prostate cancer, characterized by high prostate-specific antigen levels, high Gleason score, and/or advanced T category. Contemporary management paradigms involve advanced molecular imaging and multimodal treatment with intensified prostate-directed or systemic treatment-resources more readily available at high-volume centers.

Objective: To examine radiation facility case volume and overall survival (OS) in men with VHR prostate cancer.

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Background: Clinical evidence has demonstrated that proton therapy can achieve comparable tumor control probabilities compared to conventional photon therapy but with the added benefit of sparing healthy tissues. However, proton therapy is sensitive to inter-fractional anatomy changes. Online pre-fraction evaluation can effectively verify proton dose before delivery to patients, but there is a lack of guidelines for implementing this workflow.

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Purpose: Anal cancer affects a disproportionate percentage of persons infected with human immunodeficiency virus (HIV). We analyzed a cohort of patients with HIV and anal cancer who received modern radiation therapy (RT) and concurrent chemotherapy to assess whether certain factors are associated with poor oncologic outcomes.

Patients And Methods: We performed a retrospective chart review of 75 consecutive patients with HIV infection and anal cancer who received definitive chemotherapy and RT from 2008 to 2018 at a single academic institution.

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Purpose: We aimed to evaluate the impact of 18 F-fluciclovine PET/CT imaging on failure-free survival (FFS) post-salvage radiotherapy (SRT) for prostate cancer (PCa) recurrence.

Methods: Seventy-nine patients were recruited in a phase 2/3 clinical trial to undergo 18 F-fluciclovine PET/CT before SRT for PCa. Four patients with extrapelvic disease were excluded.

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The EMPIRE-1 (Emory Molecular Prostate Imaging for Radiotherapy Enhancement 1) trial reported a survival advantage in recurrent prostate cancer salvage radiotherapy (SRT) guided by F-fluciclovine PET/CT versus conventional imaging. We performed a post hoc analysis of the EMPIRE-1 cohort stratified by protocol-specified criteria, comparing failure-free survival (FFS) between study arms. EMPIRE-1 randomized patients to SRT planning via either conventional imaging only (bone scanning plus abdominopelvic CT or MRI) (arm A) or conventional imaging plus F-fluciclovine PET/CT (arm B).

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Purpose/objective: Given the rarity of vulvar cancer, data on the incidence of acute and late severe toxicity and patients' symptom burden from radiotherapy (RT) are lacking.

Materials/methods: This multi-center, single-institution study included patients with vulvar squamous cell carcinoma treated with curative intent RT between 2009 and 2020. Treatment-related acute and late grade ≥ 3 toxicities and late patient subjective symptoms (PSS) were recorded.

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Purpose: Postprostatectomy radiation therapy planning with fluciclovine (F) positron emission tomography (PET)/computed tomography has demonstrated improved disease-free survival over conventional only (computed tomography- or magnetic resonance imaging-based) treatment planning. We hypothesized that incorporating PET would result in larger clinical target volumes (CTVs) without increasing patient-reported toxic effects.

Methods And Materials: From 2012 to 2019, 165 postprostatectomy patients with detectable prostate-specific antigen were randomized (arm 1 [no PET]: 82; arm 2 [PET]: 83).

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Purpose: Addition of a brachytherapy boost to external beam radiation therapy (EBRT) reduces prostate cancer (PCa) recurrence at the expense of genitourinary (GU) toxicity. Whether brachytherapy boost technique, specifically low-dose-rate (LDR-BT) versus high-dose-rate (HDR-BT), impacts treatment-related toxicity is unclear.

Methods: Between 2012-2018, 106 men with intermediate/high risk PCa underwent EBRT (37.

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Background: The optimal management of patients with stage IV soft tissue sarcoma of the extremity (STSE) with distant metastases at diagnosis is unclear due to limited evidence and heterogeneity of current practice patterns. National guidelines have recommended surgical management of the primary site (SP) with or without radiotherapy (R), chemotherapy (C), and metastasectomy (M).

Methods: In the National Cancer Database (NCDB), patients with initially metastatic STSE who received definitive SP from 2004 to 2014 were identified.

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Background: Molecular imaging is increasingly used to guide treatment decisions and planning in prostate cancer. We aimed to evaluate the role of F-fluciclovine-PET/CT in improving cancer control compared with conventional imaging (bone scan and either CT or MRI) alone for salvage postprostatectomy radiotherapy.

Methods: In EMPIRE-1, a single-centre, open-label, phase 2/3 randomised controlled trial, patients with prostate cancer with detectable PSA after prostatectomy and negative conventional imaging (no extrapelvic or bone findings) were randomly assigned in a 1:1 ratio to radiotherapy directed by conventional imaging alone or to conventional imaging plus F-fluciclovine-PET/CT.

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Background: Small-cell carcinoma of the prostate (SCCP) is a rare but aggressive prostate cancer histology. We studied the reported comparative outcomes of the efficacy of radiotherapy (RT) versus surgery for nonmetastatic SCCP.

Methods: The National Cancer Database (NCDB) was queried for nonmetastatic disease diagnosed from 2004 to 2015 as SCCP (defined as having a component of SCCP) receiving a single definitive local control modality (RT or surgery).

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